Tungsten arc lamp



1927' w. ZEBROWSKI TUNGSTEN ARC LAMP Filed Jan. 20, 1925 Inx/e nnor- Wi I Is Zebv-owsKi g H is Antiorne Patented Feb. 15, 1927.

UNITED sr rEs 1,611,979 PATENT OFFICE.

WILLY ZEBROWSKI, OF BEIB-LIN-NEUKOLLN, GERMANY, ASSIGNOR TO GENERAL ELEC- TRIO COMPANY, A QORIPOBATION OF NEW YORK.

'IUNGSTEN ARC LAMP.

Application filed January 20, 1925, Serial No. 8,668, and in Germany March 13, 1924.

My invention relates to tungsten arc lamps and in part to means for starting the arc 1n such lamps.

In such lamps the method of ignition by contact between the electrodes has been employed only in connection with direct current because in such case it is possible to use an oxide or an oxide containing element as the cathode electrode inasmuch as the cathode from the standpoint of illumination is not of great importance.

When it is contemplated to use alternating current it becomes necessary that both electrodes should be of pure tungsten because each electrode alternatel becomes the anode and the cathode and both participatevitally in the illumination. However. it is a difficult matter to draw an are between two tungsten electrodes and particularly in a neutral atmosphere such as nitrogen.-

the case of lamps using pure tungsten the ignition is sometimes obtained by using a temporary high voltage. Sometimes when the atmosphere is one of the rare gases the arc is started by means of a glow ignition. The use of high voltage of course requires special apparatus and the use of rare gases in consequence of the low are voltage requires a series resistance which entails a constant loss. For this reason, the rare gas lamps. ascompared with the nitrogen filled lamps, are less efiicient and consequently less commercial.

The object of the invention is to provide means for establishing an are between pure tungsten electrodes in a nitrogen atmosphere. It is also an object of my invention to use an oxide element for bridging the electrodes normally; it is also an object to separate the electrodes from the oxide body 111 a novel manner, namely, not simultaneously, but one after another, so that the arc is first formed between the oxide body and one of the electrodes and thereafter the arc is carried over to thesecond electrode, the sec ond electrode having become heated in the meantime as a result of the formationiof the first arc. Y

vIt will be understood that in thus establishingthe arc, the electrodes are to be drawn off one after another from the intermediate piece. In one form of construction the intermediate piece may be drawn oif slantingly so as to leave one of the electrodes at a time. The two electrodes in one arrangement as. for example, theform of a disc.

may be maintained in contact normally with the oxide body by spring presssure so that as the oxide iecc is drawn ofi', one of the electrodes follbws the oxide body only ior'a short distance and then breaks while contact between the second electrode and the body persists for a somewhat longer distance before the second break takes place.

This construction possesses the advantage that the ignition is reliable and the lamp may be operated without difficulty in connection with either direct current or an alternating current.

The details of the invention are hereinafter more fully set forth and claimed reference being had to the accompanying drawing which shows the tungsten lamp of my invention in frontview.

Referring more in detail to the drawing, it will be seen that the lamp comprises the usual glass enclosure a, the foot 6, the leading inwires 0 and d, and the supporting stems e and f which support tungsten electrodes g and h respectively.

To the foot 6 there is fastened a supporting rod z, which supports the oxide element is, which latter may have any suitable sh Epe,

IS oxide body may consist of a mixture of tungsten and thorium oxide. If desired, this oxide body may be given a coating of alkaline earth metal, such as barium azide. Normally the rod '5 maintains the element against electrodes 9 and h. The supporting rod 5 is secured to a bimetallic strip 1. Furthermore, in proximity of the bimetallic strip there is a resistance heating unit m, which is interposed between the stem 0 and the supporting rod 6. Therefore, when the circuit is closed through the lamp, this element at becomes heated and beats in turn the bimetallic strip Z. The supporting rods 6 and f of the two electrodes 9 and h are adjusted so that when the element In is withdrawn one of the electrodes follows the element k a longer distance than the other. Therefore, one of the electrodes breaks with the element is, before the second electrode breaks with the same element.

With the arrangement described, when the current is turned on through the lamp, the flow takes place through the electrodes 9 and h, by way of the plate In and the glow wire m is thereby brought to a heated condition with a result that the bimetallic structure Z, is heated in turn. The latter therefore, begins to bend and thereby causes the plate I: to recede. The electrodes of course follow and shortly the electrode g, for example, breaks contact with the plate is. Therefore an arc is established between the ball 9 and the plate is. The result is that the ball becomes quite hot while the plate A: and the electrode in also become considerably heated even to a red ,e'low before it separates from the plate In. This separation takes place shortly after. due to the action of the bimetallic strip Z. \Vhcn the second electrode separates from the plate is, the are at once passes over to the second electrode h with a result that the arc continues in operation between the two tungsten electrodes 7 and it without the interposition of the plate is. When the current is turned off from the lamp the elements cool and the plate It returns to its initial position bearing; against the two electrodes ready for a repetition of action described when the current is turned on again.

While it is immaterial when alternating current is being used which electrode is connected to either side of the line that supplies the current, care should be had that when direct current is used the electrode 9, the first to separate from the element k, be connected to the line so as to serve as an anode while plate It and the second electrode h serve as cathode.

When direct current is used. the new tungsten lamp ignites effectively by using a simple series resistance and a pressure from 110 to 220 volts. When the lamp is used in connection with alternating current. a satisfactory ignition can not be obtained by using a series resistance with a voltage as low as 110. The minimum voltage with which the lamp will operate satisfactorily is 150. However it has been found that if for the series resistance a choke coil is substituted. the ignition may be obtained with a line voltage of 110 volts. The choke coil provides a novel means for enabling ignition to take place at a comparatively low line voltage. n

The structure of the lamp may be modified in that bimetallic strips of difierent shapes or of difierent dimen ions may be inserted in the supporting rods of the, ele trodes g and b, so that when the current is turned on, one electrode is caused to leave the intermediate element 7:. before the other. in this case the element k, is maintained stationary and the electrodes are the ones which are caused to move alone.

It is also possible that the bimetallic strips thus inserted into the supporting rods of the intermediate niece k can be' made in such form as to cfiect a turning of the intermediate piece during the-process of drawing away from the-electrodes so that the intersten electrodes may obviously be varied.

The intermediate piece may consist. for example, of iron, coated with a suitable material possessing high enough electronremissivity sub. for example, as barium.

It will be understood, therefore, that I do not wish to be limited to the specification embodiments illustrated and described inasmuch as, in View of the disclosure, the device may be varied without departing from the spirit of the invention or from the scope of the class contained herein.

lVhatI claim as new and desire to secure by Letters Patent of the United States, 13:

1. The method of establishing an are between two refractory electrodes in an atmosphere of neutral gas, which consists in bridging the electrodes with an element of high electronic emissivity and producing a gap between one of the electrodes and the element to start the are between the two, allowing the second electrode to remain in contact with the element after the arc is started until it becomes heated and thereafter separating the second electrode to set upthe are between the two electrodes di rectly and without theiinterposition of the element.

2. The method of establishing an are betwecn two tungsten electrodes m an atmosphere of nitrogen, which consists in bridgmg the electrodes with an element of high electronic emissivity and producing a gap between one "of the electrodes and the element to start the are between the two, allowing the second electrode to remain in contact with the.element after the are is started until it becomes heated and thereafter separating the second electrode to set up the are between the two electrodes directly and without the interposition of the element.

3. In an arc lamp, a pair of electrodes of refractory material and enclosing envelope an atmosphere of neutral gas in the onvelope and an element of high electronic emissivity, bridging the two electrodes and a means for separating one of the electrodes and the element and thereafter separating the other electrode and the element, whereby an arc is first established between one of the electrodes and the element and thereafter between the two electrodes directly.

4. In an arc lamp, a pair of electrodes of tungsten and an enclosing envelope, an

atmosphere of nitrogen in the envelope and an element of high electronic emlsivity the two eleelzodes, and means oompnsing a bimetallic ship for separat one of the eleetmdes and the element, and ereafter sepa'm the other electrode and the element, where -v an arc-is first established between one of the meat and thereafter between the two electmdes directly. t 4

5. In an arc lamp, 1 pair of metallic electrodes, and a swledendosing envelo e, an element of high electronin emissivity ridging-the two eleetmdes and means for sepand the ele said heating element arranged to be in circult with the are, when thearc is established, whereby the bridging element is retained out of engagement with the elee'trodw, while the arc is in o ration.

6 The method of establishing an an: between two metallic electrodes in an atmosphere of neutral gas, which consists in bridgmg the electrodes with an element of high electronic and rode a, gap between one of Eh electrodes a n s the element to start the are between the two, :1- lowing the second electrode to remain in contact with the element after the are is started until it becomes heahd and themafter separating the second electrode to set up the are between the two electrodes directly and without the interruption of the element.

In witnm whereof, I have hereunto set my hand this 3rd day of enner 1925.

WDZLY ZEB WSKI.

atmosphere of nitrogen in the envelope and an element of hi h electronic emisivity bridging the two e ectrodes, and means comprising a bimetallic strip for separatin one of the electrodes and the element, and thereafter separatin the other electrode and the element, where y an arc is first established between one of the electrodes and the ele ment and thereafter between the two electrodes directly.

5. In an arc lamp, a pair of metallic electrodes, and a sealed enclosing envelope, an element of high electronic emissivity bridging the two electrodes and means for sepsaid heating element arranged to be in circuit with the are, when the arc is established, whereby the bridging element is retained out of engagement with the electrodes, while the arc is in operation.

6. The method of establishing an are between two metallic electrodes in an atmosphere of neutral gas, which consists in bridgmg the electrodes with an element of high electronic emissivity and producing a gap between one of the electrodes and the element to start the are between the two, allowing the second electrode to remain in contact with the element after the arc is started until it becomes heated and there after separating the second electrode to set up the are between the two electrodes directly and without the interruption of the element.

In witness whereof, I have hereunto set my hand this 3rd day of anuary, 1925.

WILLY ZEBROWSKI.

CERTIFICATE OF CORRECTION.

Patent No. 1,617,979.

Granted February 15, 1927. to

' IILLY zssaowsxl.

above red patent requiring correcti strike out claim 2; same page, lines 118 in the printed specification of the follows: Page 2, lines 104 to 117, and 129. and page 3, lines 11 M28.

for "3, 4. 5 and 6" read "2. 3. 4 and 5" respectively; and that the said Letters Patent should he read with these corrections therein that the same may conform to the record of the ease in the Patent Office.

Signed and sealed this 22nd day of March, A. D. 1927.

Seal.

I. J. llssrs, Acting Commissioner of Patents.

CERTEFICATE 0F CORRECIEGN.

Patent No. L6H, 979. Granted February I5, 1927. to

WILLY ZEBROWSKI.

it is hereby certified tlnt error appears in the printed specification of the above numbered patent requiring correctioh as follows: Page 2, lines 104 to 117, strike out claim 2; same page, lines 118 and 129, and page 3, lines 11 and 28. [or "3. 4. 5 and 6" read "2, 3. 4 and 5" respectively; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this Zhd day of March, A. D. 1927.

I. J. lloore. Seal. Acting Gomiuioner'of Patents. 

